Personal computer systems utilize an input/output (I/O) system that connects to peripheral devices which are needed to have an operable system. These peripheral devices are typically a keyboard, a mouse, and printer. These devices have been present from the early days of personal computers and are therefore known as legacy I/O, or XIO and now known by the term as Super I/O. The list of components that are utilized to make a Super I/O unit of a personal computers change with every generation of personal computers. New components have been added to the Super I/O such as SMbus controllers, CPU cooling fan controls and IRDA. The Super I/O unit is connected to the personal computer host by a special low bandwidth bus called the Low Pin Count (LPC) bus.
Portable computers commonly known as notebook or laptop computers, may use a docking station to connect the computer to peripheral devices, a larger monitor and a power source. When the laptop computer is docked, some of the Super I/O components functionality is transferred over to the docking station. If the LPC bus is extended to the docking station, additional connectors will have to be added to both the laptop computer and the docking station. This adds additional cost to both the laptop computer and the docking station and adds to the weight of the laptop computer. If the LPC bus is not extended, the problem is how to exchange data between the laptop computer CPU and the docking station's Super I/O components.
FIG. 1 shows a block diagram of the current configuration for extending the I/O through the docking connector into the docking station, generally as 100. In FIG. 1, the host computer 102 communicates with the Super I/O chip 106 via the LPC bus 104. Bus 104 is a bi-directional bus. The Super I/O chip breaks out the commands to each of the peripheral devices at outputs 108. Output 108a is for the line printer, outputs 108b and c for the communications port, output 108d and e are for the PC/2 port, output 108f is for the FDD (floppy disk drive) and output 108g is for the fast IR. These lines 108a–108g are extended through the docking connector into the port replicator of the docking station.
PCI_Express is a new architecture utilizing point-to-point transmission having a high speed which is scalable for future improvements and which will become the replacement for current PCI (Peripheral Component Interconnect) parallel bus architecture in use today. PCI_Express would provide a vehicle for communicating between the CPU of a portable computer and peripheral devices connected to a docking station, except that the command structure and connection type is incompatible with PCI_Express. The LPC bus is bi-directional half duplex bus where as PCI_Express is a unidirectional full duplex point-to-point fabric. The commands on the LPC bus are of varying length which makes it difficult to inject this data into a the data flow of another system.
Accordingly, there is a need for a low cost means of interfacing the CPU of a host computer with peripherals connected to a docking station.